Trump warns world against business with Iran as sanctions return

US President Donald Trump warned the world Tuesday against doing business with Iran as Washington reimposed “the most biting sanctions ever” on the Islamic republic, triggering a mix of anger, fear and defiance in Tehran. Trump’s May withdrawal from a landmark 2015 nuclear deal with Tehran had spooked investors and triggered a run on the Iranian rial long before the punishing sanctions went back into force. Iran’s markets were actually relatively buoyant, with the rial strengthening by 20 percent since Sunday after the government relaxed foreign exchange rules and allowed unlimited, tax-free gold and currency imports.